In a vehicle or the like which runs with electric power generated by a fuel cell system, electric power generation by the fuel cell is stopped under a running condition of relatively low load or the like. That is, so-called idle-stop is executed in some cases. During idle-stop, air supply to a cathode is stopped. Oxygen that remains in the cathode is consumed by reacting with hydrogen that permeates to the cathode, whereby a stack total-voltage gradually lowers.
Idle-stop is terminated when a charged amount of batteries lowers below a predetermined threshold value or when load is increased by speed-up request or the like. However, it requires time from an instant when fuel supply is re-started to an instant when current is ready to be taken out. In addition, because of electric motor characters, even with the same accelerator operations, a response performance of electric power required upon acceleration becomes higher as vehicle speed increases. Then, a battery's dischargeable electric power is determined by the battery's state of charge, temperature, deterioration state, and the like.
Accordingly, if an electric motor for driving is driven by an output according to a magnitude of acceleration request upon recovery from idle-stop, an electric power that is not sufficiently provided with an electric power generated by the fuel cell would be supplied from the battery. As a result, over-discharge of the battery would occur. To the contrary, if the output of the electric motor is limited, drivability would be lowered.
Therefore, in JP4182732, when an increase in requested electric power is presumed, prior to recovery from idle-stop, supply of hydrogen or the air is re-started. Furthermore, also when the stack voltage lowers below a predetermined voltage during idle-stop, supply of hydrogen or the air is re-started. By way of these controls, delay of power generation on the recovery from idle-stop is avoided.